1. Field of the Invention
The present invention relates to a display apparatus provided with a portable electronic device such as a digital camera.
2. Description of the Related Art
In recent years, portable electronic devices such as digital cameras have been significantly reduced both in thickness and cost.
A display apparatus, such as a liquid crystal panel, equipped with a digital camera accounts for a large percentage of the body of the digital camera. Liquid crystal panels generally include thin glass substrates, and thus prone to damage by external force or to inconsistencies in display caused by change in orientation due to flexure. To overcome these drawbacks, a screen protector composed of a colorless, transparent resin with excellent light transmittance, such as polymethyl methacrylate, is provided with the exterior cover of a liquid crystal panel to protect the panel such that the panel is prevented from direct exposure to the outside.
Conventionally, a screen protector has been attached to a display apparatus often by adhesion to an exterior cover. On the other hand, a liquid crystal panel has been often attached to the body of a digital camera. This is because, in the case of a liquid crystal panel, a flexible substrate to be adhered to the body of a digital camera is required to be shortened as much as possible for the purpose of cost saving. Taking variations in assembling and parts into consideration, a large clearance needs to be created between a screen protector and a liquid crystal panel. This has been one factor which prevents reduction in the thickness of a digital camera.
Japanese Patent Laid-Open No. 07-209635 discloses a method for reducing the thickness of a digital camera by affixing a colorless, transparent resin screen protector directly to a liquid crystal panel to decrease the clearance between the screen protector and the liquid crystal panel. Japanese Patent Laid-Open No. 07-209635 also discloses a technique for filling or cohereing a gel-state or low-repulsion-elastic transparent resin between the screen protector and the liquid crystal panel to achieve a higher viewability.
However, the method disclosed in Japanese Patent Laid-Open No. 07-209635 adopts a special technique to affix the screen protector to the liquid crystal panel, thus causing a problem of increase in cost.
One solution to this problem is to affix the screen protector to the liquid crystal panel by inserting a spacer therebetween. The spacer is designed in a three-layered structure including, in order from outside, a first double-sided adhesive tape, a PET sheet and a second double-sided adhesive tape to ensure a minimum-required clearance for preventing a contact of the screen protector and the liquid crystal panel in a thickness direction. The spacer is approximately square-shaped not to decrease the viewability of the center portion of the display surface of the liquid crystal panel. In addition, the spacer tightly shuts a space between the screen protector and the display surface of the liquid crystal panel, which avoids entry of dust and the like into the display surface.
However, such adhesion of the screen protector and the liquid crystal panel with the spacer has a problem. The problem is that, in case of change in environment (especially under high temperature and high humidity), the screen protector changes its shape to come into contact with the display surface of the liquid crystal panel at the vicinity of the center portion of the display area, causing contact cracks on the display surface of the liquid crystal panel. One possible cause is that the thermal expansion coefficient of a transparent resin employed as a screen panel is greater than those of a glass employed as a PET sheet or as a liquid crystal panel and a metal employed as a bezel. This difference in thermal expansion coefficient makes the transparent resin easily change its shape by an increase in temperature. Another possible cause is that if a transparent resin employed as a screen panel absorbs humidity, it easily changes its shape.
A possible solution of expanding the clearance by increasing the thickness of the spacer to prevent a contact of the screen protector and the liquid crystal panel, however, cannot achieve reduction in thickness.